My comp specs are:
2gb ram
Intel dual core E5200 running @ 2.5 GHZ
Intel DG31PR mobo
80 gb hdd
Sony optical dvd drive

How much do u think I should sell it for in india?

Depending on what it came with. If its just to tower than $300-$400. If it comes with everything than about $450-500 depending on what size the monitor is. (That's around 14,000-23,000 in India Rupees.)